With some exceptions, in liquid crystal display devices, a liquid crystal display panel is combined with a backlight. In large liquid crystal display devices such as ones incorporated in television sets, a plurality of straight tube light source lamps are often arrayed at a predetermined interval in a backlight chassis with a view to distributing required amount of light in every corner of a screen. An example of the structure of such large liquid crystal display devices is shown in FIG. 12.
FIG. 12 is an exploded perspective view of components of a liquid crystal display device. Here, the components are arranged assuming the liquid crystal display device is to be assembled such that a display surface faces up. What lies at the bottom is a backlight chassis 1 formed of sheet metal. Over the backlight chassis 1, a reflector sheet 2 is laid. Over the reflector sheet 2, a plurality of light source lamps 3 for backlighting are arranged. Although straight type cold cathode tubes are generally used as light source lamps for backlighting, it is also possible to use any other types of lamps, for example, hot cathode tubes, xenon lamps, and the like.
Over the light source lamps 3, an optical sheet group 4 is arranged, the optical group 4 including a diffusion plate, a lens sheet, a polarizing reflection sheet, a diffusion sheet, etc. The optical sheet group 4 is used for adjusting the characteristics of light which the light source lamps 3 emit.
The optical sheet group 4 is fitted to the backlight chassis 1 with a rectangular frame 5. Over the frame 5, a liquid crystal display panel 6 is arranged. At the top tier, a rectangular bezel 7 is arranged. The bezel 7 serves to fix the liquid crystal display panel 6 with respect to the backlight chassis 1, and also serves to improve the appearance of the liquid crystal display device as a whole.
The backlight chassis 1 is rectangular as seen in a plan view, and has the shape of a tray with its rim erected at its periphery. At both ends of the backlight chassis 1 are formed fitting portions 9 for sockets 8 that are fitted in end parts of the light source lamps 3. Each of the fitting portions 9 is a through hole with a predetermined shape, into which two sockets 8 are inserted. A plurality of fitting portions 9 are formed in line along the shorter sides of the backlight chassis 1. The sockets 8 are electrically connected to a control circuit board in a control box (not shown) provided at the bottom of the backlight chassis 1.
Each of the light source lamps 3 is long, and sounds when vibration is transmitted to it. Moreover, if an impact force acts on the light source lamp 3, there is a risk of breakage. To avoid this, a middle part of the light source lamp 3 is fixed to the backlight chassis 1 with a lamp clip 20.
The structure of a lamp clip 20 is shown in FIG. 14. In the lamp clip 20, a lamp gripper 22 with the shape of “C” open at the top is provided on the upper surface of a plate-shaped base 21 which is rectangular as seen in a plan view. The lamp gripper 22 is for holding a light source lamp 3 with its elasticity; a total of two lamp grippers 22 are provided on the base 21, one near either end of the base 21 in the longitudinal direction of it. On the lower surface of the base 21, two fitting studs 23 which have the shape of a snap stud with a bulged head portion and a slotted groove are formed in the longitudinal direction of the base 21 at an interval. The whole lamp clip 20 is integrally formed of an elastic synthetic resin.
In the backlight chassis 1 and the reflector sheet 2 attached on the upper surface of the backlight chassis 1, a fitting hole 10 for the lamp clip 20 is formed. The fitting hole 10 is for snap-engaging the fitting stud 23, and is arranged in a pair. When the fitting stud 23 is pressed against the fitting hole 10 from above, the bulged head portion of the fitting stud 23 shrinks and passes through the hole. When the head portion of the fitting stud 23 comes out from the lower surface of the backlight chassis 1, it springs back and bulges. In this way, the lamp clip 20 is fixed.
As shown in FIG. 13, a light source lamp 3 is held by lamp clips 20 at two places somewhere in the middle of itself. One lamp clip 20 holds two light source lamps 3. Thus, the light source lamps 3 are in a pair and, along the length direction of the pair of light source lamps 3, two lamp clips 20 are arranged at an interval.
Holding middle parts of the light source lamp 3 by the lamp clip 20 prevents the light source lamp 3 from vibrating and sounding. Moreover, even if an impact acts on the backlight chassis 1, it is less likely that the light source lamp 3 bends and breaks.
The lamp clip 20 is formed of a synthetic resin with poor thermal conductivity; even so, a predetermined percentage of heat generated by the light source lamp 3 is transmitted to the backlight chassis 1. As a result of heat being taken away, the brightness of the light source lamp 3 is reduced at places where the lamp clips 20 are. If the lamp clips 20 are aligned in the shorter-side direction of the backlight chassis 1, a visible band with lower brightness appears. Thus, to prevent this, the positions of the lamp clips 20 are spread out. Specifically, as shown in FIG. 13, between adjacent pairs of light source lamps 3, the position of the lamp clips 20 is deviated in the length direction of the light source lamp 3, so that the lamp clips 20 are in a staggered arrangement. In this way, parts with lower brightness are spread out, and become less annoying.
Examples of the lamp clip described above are disclosed in Patent Documents 1 and 2.    Patent Document 1: JP-A-2006-32358    Patent Document 2: JP-A-2005-19420